vb.net use function from other form - vb.net

Question

I am in a situation where i have a single helper class that i re-use on most of my forms. and it happens that my helper class needs to call a function from that form as well
Public Class Form1
Dim hc As HelperClass
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
hc = New HelperClass
End Sub
Private Sub someForm1Sub()
'do something
End Sub
End Class
Public Class Form2
Dim hc As HelperClass
Private Sub Form2_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
hc = New HelperClass
End Sub
Private Sub someForm2Sub()
'do something
End Sub
End Class
Public Class Form3
Dim hc As HelperClass
Private Sub Form3_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
hc = New HelperClass
End Sub
Private Sub someForm3Sub()
'do something
End Sub
End Class
Public Class HelperClass
'i need to call here someForm1Sub(), someForm2Sub(), someForm3Sub()
'but it bases on which form uses this class
End Class
i think that there are many ways to do this. I have read some about delegate function, but i do not know how to pass a delegate to other class. I am using vb.net 2010. Please provide the best way to do this
please reply thanks.

Answer 1

You can pass a delegate to a method using the AddressOf keyword. For example,
Public Sub Test()
' Make Foo() call the Bar() method.
Foo(AddressOf Bar)
End Sub
Public Sub Foo(d As Action)
' Call the delegate.
d()
End Sub
Public Sub Bar()
Console.WriteLine("Bar was called.")
End Sub
But, as you say, there are many ways you could do this. One possible solution which may be a bit nicer than passing delegates (especially if there are a few methods in the form that could be called by the helper class) would be to have Form1, Form2 and Form3 all implement an interface, and have the HelperClass call a method on the interface. An instance of the interface could then be given to HelperClass in its constructor.
For example,
Public Interface IForm
Sub DoStuff()
End Interface
Public Class Form2
Implements IForm
Dim hc As HelperClass
Private Sub Form2_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
hc = New HelperClass(Me)
End Sub
Public Sub DoStuff() Implements IForm.DoStuff
' Do stuff here.
End Sub
End Class
Public Class HelperClass
Private _form As IForm
Public Sub New(form as IForm)
_form = form
End Sub
Public Sub MakeTheFormDoStuff()
_form.DoStuff()
End Sub
End Class